package HashMap;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by wangyg 
 * on 2017/6/13 10:29
 */
public class TestNull {
	public static void main(String[] args) {
		Map<String,String> map=new HashMap<>();
		map.put(null,"123");
		map.put(null,"456");
		String put = map.put("123", "456");
		String put1 = map.put("123", "777");
		System.out.println(put+":"+put1);
		System.out.println(map.toString());
	}
}
